Method UpdateNetstackIPs

wgengine/netstack/netstack.go:705–810

UpdateNetstackIPs updates the set of local IPs that netstack should handle from nm. TODO(bradfitz): don't pass the whole netmap here; just pass the two address slice views.

(nm *netmap.NetworkMap)

// TODO(bradfitz): don't pass the whole netmap here; just pass the two
// address slice views.
func (ns *Impl) UpdateNetstackIPs(nm *netmap.NetworkMap) {
	var selfNode tailcfg.NodeView
	var serviceAddrSet set.Set[netip.Addr]
	if nm != nil {
		ns.atomicIsLocalIPFunc.Store(ipset.NewContainsIPFunc(nm.GetAddresses()))
		if buildfeatures.HasServe {
			vipServiceIPMap := nm.GetVIPServiceIPMap()
			serviceAddrSet = make(set.Set[netip.Addr], len(vipServiceIPMap)*2)
			for _, addrs := range vipServiceIPMap {
				serviceAddrSet.AddSlice(addrs)
			}
			ns.atomicIsVIPServiceIPFunc.Store(serviceAddrSet.Contains)
		}
		selfNode = nm.SelfNode
	} else {
		ns.atomicIsLocalIPFunc.Store(ipset.FalseContainsIPFunc())
		ns.atomicIsVIPServiceIPFunc.Store(ipset.FalseContainsIPFunc())
	}

	oldPfx := make(map[netip.Prefix]bool)
	for _, protocolAddr := range ns.ipstack.AllAddresses()[nicID] {
		ap := protocolAddr.AddressWithPrefix
		ip := netaddrIPFromNetstackIP(ap.Address)
		if ip == v4broadcast && ap.PrefixLen == 32 {
			// Don't add 255.255.255.255/32 to oldIPs so we don't
			// delete it later. We didn't install it, so it's not
			// ours to delete.
			continue
		}
		p := netip.PrefixFrom(ip, ap.PrefixLen)
		oldPfx[p] = true
	}
	newPfx := make(map[netip.Prefix]bool)

	if selfNode.Valid() {
		for _, p := range selfNode.Addresses().All() {
			newPfx[p] = true
		}
		if ns.ProcessSubnets {
			for _, p := range selfNode.AllowedIPs().All() {
				newPfx[p] = true
			}
		}
	}

	for addr := range serviceAddrSet {
		p := netip.PrefixFrom(addr, addr.BitLen())
		newPfx[p] = true
	}

	pfxToAdd := make(map[netip.Prefix]bool)
	for p := range newPfx {
		if !oldPfx[p] {
			pfxToAdd[p] = true
		}
	}
	pfxToRemove := make(map[netip.Prefix]bool)
	for p := range oldPfx {